1. Field of the Invention
The present invention relates to implants for the spine and, more particularly, to posterior spinal implants for lumbar vertebrae stabilization/fixation.
2. Background Information
As we age various changes can occur in the body. For instance, the ligaments of the spine can thicken and calcify (i.e. harden from deposits of calcium), bone and joints may enlarge, bone spurs called osteophytes may form, spinal discs may collapse and bulge (i.e. herniate) or one vertebra may slip over another (spondylolisthesis). Any one or these conditions and/or others can cause what is known as spinal stenosis. Spinal stenosis is a narrowing of the bony spinal canal. While some people are born with this condition, most often spinal stenosis is the result of one of the above-identified degenerative conditions that develop in mainly the middle-aged and elderly population.
In this regard, spinal stenosis may be considered as the gradual result of aging and “wear and tear” on the spine from everyday activities. Such degenerative or age-related changes in our bodies can lead to compression of nerves (i.e. pressure on the nerves that can cause pain and/or damage). Symptoms of spinal stenosis include leg pain (“pins and needles”) that can limit standing, walking, self-supporting daily activities, work, social and recreational pursuits. Lack of activity because of spinal stenosis may lead to obesity, depression and general physical deterioration.
Spinal stenosis is one of the most common reason for back surgery in people over the age of 50 in the United States. While there are various non-surgical treatments for spinal stenosis, various spinal decompression surgical procedures may be utilized to reduce or eliminate the symptoms of spinal stenosis or other spinal problems. Such procedures include a laminectomy a laminotomy, a foraminotomy or a facetectonomy.
Another surgical treatment for spinal stenosis and other spinal problems is known that is less invasive than the above surgical procedures. This other surgical treatment involves implanting a device between bony projections of adjacent vertebrae, particularly, but not necessarily, between spinous processes of the adjacent vertebrae. This achieves interspinous process decompression for alleviating spinal stenosis and other spinal problems. However, when spinal decompression, fixation or stabilization is desired between a lower lumbar vertebrae and the pelvis, prior art interspinous process decompression implants do not work.
In view of the foregoing, it is therefore desirable to provide a spinal implant for interspinous decompression of lower lumbar vertebrae relative to the pelvis. Accordingly, there exists a need for a spinal implant that provides vertebral stabilization/fixation of a lumbar vertebra relative to the pelvis.